1. Field of the Invention
The present invention relates to a spindle for a spinning frame or a twisting machine. More particularly, the present invention relates to a spindle for a spinning frame or a twisting frame which is operated in such a manner that a tail yarn is formed on a full bobbin and, at the cop changing operation, the tail yarn is taken out from the full bobbin and wound in the form of a loop on the spindle.
2. Description of the Related Art
It is known that in a spinning frame, when a bobbin on a spindle becomes full, the full bobbin is doffed from the spindle and an empty bobbin is donned on the spindle, that is, the so-called cop changing operation is carried out. This cop changing operation has heretofore been manually performed, but recently, automatic cop changing has been adopted as a labor-saving measure. Automatic cop changing is roughly divided into the so-called simultaneous doffing method in which cop changing is carried out simultaneously in all the spindles by a cop changer attached to the spinning frame, and the group doffing method in which a doffer intermittently travels along the front face of the spinning frame and the cop changing operation is conducted sequentially for a predetermined number of spindles.
Nevertheless, whether manual cop changing or automatic cop changing is adopted, the disposal of the tail yarn after cutting is an important problem. More specifically, at the cop changing operation, after a full bobbin is held and doffed from a spindle, the tail yarn extending between the full bobbin and the spindle is cut by an appropriate means, but subsequent winding becomes impossible if the cut tail yarn is not held at a predetermined position (of course, there is a certain allowable range for this position) on the surface of the spindle and the tail yarn is not gripped between an empty bobbin and the spindle when the empty bobbin is donned. To ensure such holding and gripping, there is ordinarily adopted a method in which a barrel winding and tail winding are formed on the full bobbin. By doffing the full bobbin from the spindle, the tail winding is pulled and unwound and is turned on the spindle to form a loop winding on the spindle, and the tail yarn is cut and held at the predetermined position.
However, in the above-mentioned method, since only a slight frictional resistance between the loop winding and the spindle is utilized, detachment of the loop is caused at the time of cutting the tail yarn by the tension imposed on the tail yarn or for other reasons, and therefore, the operation reliability is low and the method is practically non-operative. As a means for overcoming this defect, there is adopted an automatic group doffing method in which a tail yarn wound in a loop is once held by a holding member attached to a doffer and is then cut. In this method, since a special holding device is necessary, the structure becomes complicated and the manufacturing cost is increased. Furthermore, in this method, adjustment of the timings for inserting an empty bobbin and releasing the held tail yarn is very difficult and satisfactory results cannot be obtained.
As pointed out above, a certain countermeasure is taken in the group doffing method, though this countermeasure is still insufficient. However, in the simultaneous doffing method, because of simultaneous doffing of all the bobbins and because of other production limits, attachment of a tail yarn holding device such as mentioned above is substantially impossible. At present, no substantial countermeasure is available, and in the case of manual operation, of course, no means can be adopted.
As the spindle for the manual cop changing operation, a spindle provided with a special cutting device is proposed in Japanese Unexamined Utility Model Publication (Kokai) No. 45-28573. According to this proposal, a chip piece having a peripheral groove is formed in the upper portion of the spindle, and a spiral ring is fitted in this peripheral groove. At the cop changing operation, the yarn wound in a loop is assuredly held in the spiral ring and is cut. However, since the tail yarn intrudes into the spiral ring and is cut, the remaining yarn is always left in the upper portion of the spindle and is accumulated on each spindle, and thus, since the disposal of these remaining yarns is troublesome, the method is not practically carried out.